From: Paul Jackson <pj@sgi.com>
To: Andrew Morton <akpm@osdl.org>
Cc: guillaume.thouvenin@bull.net, linux-kernel@vger.kernel.org,
matthltc@us.ibm.com
Subject: Re: [BUG linux-2.6.15-rc] process events connector - soft lockup detected
Date: Fri, 25 Nov 2005 14:29:52 -0800 [thread overview]
Message-ID: <20051125142952.02d63801.pj@sgi.com> (raw)
In-Reply-To: <20051125115725.3ff23590.akpm@osdl.org>
Andrew wrote:
> I note that copy_process() also calls cpuset_fork() under
> write_lock_irq(&tasklist_lock) which is a) inefficient and b) forbidden
> according to the nice comment over task_lock().
Nice catch - thanks. It was (perhaps) only inefficient until recently, because
cpuset_fork() didn't do any locking - just an atomic cpuset counter increment.
But with the locking overhaul that went into Linus's tree Oct 31, 2005,
cpuset_fork() now takes task_lock(), to guard against cpuset.c attach_task()
invalidating the task->cpuset pointer as cpuset_fork is dereferencing it.
I will look into preparing a patch that moves cpuset_fork() outside the
write_lock_irq().
--
I won't rest till it's the best ...
Programmer, Linux Scalability
Paul Jackson <pj@sgi.com> 1.925.600.0401
prev parent reply other threads:[~2005-11-25 22:30 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-25 13:42 [BUG linux-2.6.15-rc] process events connector - soft lockup detected Guillaume Thouvenin
2005-11-25 19:47 ` Andrew Morton
2005-11-25 19:57 ` Andrew Morton
2005-11-25 22:29 ` Paul Jackson [this message]
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